1. Field of Invention
The present invention relates to the technology for controlling position input in a portable electronic apparatus, in particular to an information input device for a portable electronic apparatus and a method for controlling the input device.
2. Description of Prior Art
In the rapid evolution of computer technology, the invention of the mouse has brought considerable convenience to people, the mouse thus has been given a full play to its role and maintained a constant development in its own technical aspect. From the original X/Y-axis mechanical mouse to the photoelectric reflective mouse and the photoelectric-coded mechanic wheel rotary mouse and further to the current optical-image position sensor mouse, the mouse has advanced remarkably in terms of performance, reliability, precision and so on. Moreover, the functions of the mouse have been greatly expanded, for example, with the addition of roller operation.
With the development of information technology and the ever growing demand for mobile computation, new requirement has been proposed on the position input device of a mobile or portable computer, that is, the position input device in the portable computer needs a size small enough for handy carrying; and it should be integrated with the portable computer so as to avoid any plug-in or pull-out action during the use of the portable computer and the need for any wire dangling externally, thereby providing a tiny and clean appearance as a whole.
It is constrained to integrate a mouse and its variations, such as track ball, into a portable computer due to the relatively large size of the mouse itself, especially the rolling ball in it. Thus the application of the mouse to a notebook computer suffers inevitable limitation as a whole. As to the mouse itself, its design has considered the requirement of people: first, it is suitable for manipulation with hand since the fingers can remain curved naturally and only need to apply a slight force as the wrist moves; second, it can be moved in a relatively large area with very high accuracy and sensitivity. Thanks to these merits, the mouse-like position input devices are necessary for some occasions with accurate positioning requirements, such as cartography and game playing.
In addition to the ordinary plug-in mouse, there are mainly three types of integrated position input devices commonly used in current portable computers. The first type refers to a trackpoint, which is embedded at certain position in the middle of a keyboard. A position signal is generated from the shaking of the trackpoint caused by a user's fingers, and the position of a cursor on a display is determined by detecting the change in the signal. The second type is a trackpad, which is a small touch window disposed below or adjacent to a keyboard. When a user moves his or her fingers on the window, the change in the position of the fingers is perceived through resistors, capacitors or inductors underlying the window. The third type is a touchpanel, usually disposed below a display screen as a perceptive device layer and generally divided into these categories, such as resist, capacitance, inductance and infrared. The touchpanel can also be equipped with an auxiliary positioning device, for example, stylus, magnetic pen or optical pen.
Among the three types of position input devices, the trackpoint has the advantage in its size much smaller than that of a key in a keyboard. Unfortunately, the trackpoint is inconvenient to manipulate due to its inconformity to the habits of most users. Besides, the fingers of a user have to consistently apply certain force during the movement of the cursor; the operation of positioning has a lower precision since the distance and speed for displacing a cursor are determined based on the force applied by the fingers; and keys for control operation are spaced a bit far away from the trankpoint, which makes a user have to stretch his or her fingers (thumb and index finger) or use both hands to carry out operations.
The touchpanel is more intuitive such that a user can operate directly on a displayed image. It enables handwriting input and is suitable for apparatuses with no keyboard, such as computer with flat-panel display or PDA. The accuracy of the touchpanel is not satisfactory, however, and given the existing technology, its input speed is far behind that of the combination of keyboard and mouse.
The trackpad is good at controllability and can be manipulated with a single hand. Moreover, it is intuitive, small and durable, and therefore widely used in the notebook computer. The trackpad generally has two types, resist-type and capacitance-type, and the latter has developed a more advantageous position detection method in terms of overall performance.
Now referring to FIG. 1, which is a schematic diagram for the capacitance-type position detection method and in which the trackpad comprises an underlying board 2, a surface insulating layer 3 and sensor strips 4 and 5. The sensor strips 4 and 5 forms a fixed sensor array by use of the standard PCB (Printed Circuit Board) or flexible circuit technology, and voltage is applied on the four corners of the trackpad and forms a fixed electric field. When a finger 1 moving on the surface layer, a change is caused in the capacitance of the sensor strip closest to the finger 1, and a current is generated by the electric field based on the change in capacitance. Then, with the measurement by a controller (not shown), the position of the finger can be calculated based on the ratio difference in the distance between the current and the four corners. The specific principle is shown in FIG. 2, and the used formula is X=i2/I*a, Y=i3/I*b, I=i1+i2+i3+i4, where a and b represents length and width, respectively.
It should be noted that the capacitance-type trackpad is reactive to finger and palm but not to nail, so the capacitance-type trackpad is characterized in its sensitivity to human body capacitance but not to contact area. The reason is that any influence from a large contact area is removed when the capacitance-type trackpad eliminates the interference of noise caused by static electricity, and only the position of the center of the contact area is recorded, therefore it cannot distinguished whether a finger or a whole palm moves on the surface layer.
Although popular with the notebook computer, the trackpad is indeed less controllable than an ordinary mouse. This serves as a key reason for presenting a mouse accompanying a notebook computer sold out.
The unsatisfactory controllability of the trackpad can be generally attributed to the following factors. The first factor is related to the location of the trackpad which usually lies at a position below a keyboard and near the space key. Since the space key is often pressed with a thumb, and the thumb tends to touch the trackpad during actual operation, the position of a cursor is easy to be displaced by unintentional touch of the thumb, and even misoperations, such as input at an incorrect position, would occur due to a high sensitivity of the trackpad, thereby adversely lowering the efficient of keyboard input. Furthermore, it is difficult to operate with only one hand since the relative location of keys and the trackpad is unsuitable for single-hand operation. Some complex cursor and key manipulations, for example, game playing, drawing, etc., are not easy to be completed with the trackpad since its utilizing manner is different from that of an ordinary mouse and hence inconvenient and inflexible when compared to the mouse.
In the technical solution disclosed in Japanese Patent Document JP 20000336810, various functions are provided at different positions of a trackpad. This can facilitate trackpad manipulation to some extent while fulfilling several functions, such as scrolling and window operation. In addition, some customized functions can be provided. Referring to FIG. 3, the trackpad 10 comprises a track region 34, four regions 38a, 38b, 38c and 38d for defining various functions and provided at four corners, two keys 18, a region 36 having up- and down-scrolling functions, a switch 33 and a indicator light 35 of the trackpad. The provision of the switch 33 primarily aims to prevent any misoperation since the thumbs tend to touch the trackpad 10 and result in false actions of a cursor when a use inputs characters on a keyboard with both of his or her hands. With the provision of the switch 33, however, the trackpad 10 can be turned off and the indicator light 35 becomes off in the process of input via the keyboard. When the trackpad 10 is used for operations related to position, the switch 33 is on and the indicator light 35 is turned on such that the trackpad 10 can take effect as usual.
Though the above method brings the advantage of preventing any misoperation, it gives rise to some unnecessary troubles. First, the switch has to be searched with a user's fingers, and if the fingers cannot touch the switch immediately, the user has to check where the switch is with his or her eyes, which draws the user's attention away from the screen and is adverse to his or her work efficiency. Meanwhile, the action of switching between position input and character input has to be added and hence cause inconvenience to the user. In the case of having no knowledge in advance as to whether the trackpad switch is on, the user has to check whether the indicator light is lit on or to test whether the trackpad works normally. This also adds to inconvenience undesired by the user.
English Patent Document GB2380584 discloses a method for preventing misoperation caused by a thumb, the principle of which is, when it is detected that the keyboard of a notebook computer is been stricking by a user, the trackpad is turned off automatically for a while or the input from the trackpad is neglected, while the trackpad is turned on automatically when it is detected that the user temporarily stops striking the keyboard, and hence the probability of misoperation on the trackpad can be significantly reduced.
This method has obvious drawbacks. First, the user will not continuously tap the keyboard when input on the keyboard, especially when he or she is writing an article and needs some time for contemplation. Therefore, pause and temporary stop often occur in the process of input on the keyboard, and the unintended touch on the trackpad happening just after a pause and at the start of tapping the keyboard again also leads to misoperation. Second, the frequency switching between the trackpad and the keyboard is necessary for many occasions, the fact that the trackpad can be turned on only when the keyboard input is stopped slows down the speed of switching between the keyboard and the trackpad and hence affects the efficiency of input. Therefore, this method cannot eliminate misoperation completely but can reduce the probability of misoperation only to some extent, and it makes the latency for switching longer and the operation efficiency for mixed input of text and graphics degraded.